融液冷却法による B_2O_3-Na_2O 系二成分系ガラスの生成に対する粘度の役割

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The glass-forming region in the B_2O_3-Na_2O system was tried to interpret on the basis of an assumption concerning the glass-forming ability of a substance that higher viscosity melts will make a glass when quenched at an appropriately rapid rate, while lower viscosity melts will not. Ten grams of B_2O_3-Na_2O melts were water-quenched at a rate of 7℃/sec, and two glass-forming regions were determined. The upper glass region was 100〜61 mole per cent B_2O_3 and the lower glass region was 32〜28 mole per cent B_2O_3. Viscosity was measured by a counter-balanced viscometer at elevated temperatures above the liquidus temperature, and the liquidus viscosity log η_l was obtained for the compositions of 100〜25 mole per cent B_2O_3. The liquidus viscosity curve plotted as a function of B_2O_3 content for the B_2O_3Na_2O system exhibited two maxima and two minima in viscosity. It was found that the glass regions, 100〜61 and 32〜28 mole per cent B_2O_3, corresponded quite closely with the regions where the liquidus viscosity was higher than log η_l (poise) =0〜0. 1. The single-bond strength B_M_o and the Rawson's parameter B_<M-O>/T_l for glass formation were calculated and were compared with the glaring regions of this system. These parameters were found unsatisfactory to explain the glaring ability of the lower glass region. But the liquidus visco-sity described rather quantitatively the existence of the separate glass regions in the B_2O_3Na_2O system.
社団法人日本材料学会の論文
1981-06-15

融液冷却法による B_2O_3-Na_2O 系二成分系ガラスの生成に対する粘度の役割

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